M. Eriksson, J. Osán, J. Jernström, D. Wegrzynek, R. Simon, E. Chinea-Cano, A. Markowicz, S. Bamford, G. Tamborini, S. Török, G. Falkenberg, A. Alsecz, H. Dahlgaard, P. Wobrauschek, C. Streli, N. Zoeger, M. Betti
Source term identification of environmental radioactive Pu/U particles by their characterisation with non-destructive analytical techniques
Spectrochimica Acta Part B 60 (2005) 455-469


Abstract

Six radioactive particles stemming from Thule area (NW-Greenland) were investigated by gamma-ray and L X-ray spectrometry based on radioactive disintegration, scanning electron microscopy coupled with energy-dispersive and wavelength-dispersive X-ray spectrometer, synchrotron radiation based techniques as microscopic X-ray fluorescence, microscopic X-ray absorption near-edge structure (µ-XANES) as well as combined X-ray absorption and fluorescence microtomography. Additionally, one particle from Mururoa atoll was examined by microtomography. From the results obtained, it was found out that the U and Pu were mixed in the particles. The U/Pu intensity ratios in the Thule particles varied between 0.05 and 0.36. The results from the microtomography showed that U/Pu ratio was not homogeneously distributed. The 241Am/238+239+240Pu activity ratios varied between 0.13 and 0.17, indicating that the particles originate from different source terms. The oxidation states of U and Pu as determined by µ-XANES showed that U(IV) is the preponderant species and for Pu, two types of particles could be evidenced. One set had about 90% Pu(IV) while in the other the ratio Pu(IV)/Pu(VI) was about one third.


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